Dyeing



' Patented Aug. '11, .1942- UNITED STATE s PATENT OFFICE DYEING GeorgeHolland Ellis and Alexander James Wesson, Spondon, near Derby, England,assignors to Celanese Corporation 01' tion of Delaware America, acorpora- No Drawing. Application August 3,1940, Serial No. 351,202. InGreat Britain ,September 20,,.

8 Claims.

This invention relates to the dyeing of textile In the partialsa'ponificationof cellulose ester fibres, e. g. with caustic alkalisolutions, the reduction of acidyl content is not usually uniformthroughout the cross-section of the fibre, a product being obtained inwhich the core is substantially unaltered while'the cuticular sheath isconverted to regenerated cellulose or, at least, is so low in acidylcontent as to have substantially the same behaviour towards dyestufis asregenerated cellulose. In this speciilcation the term surface-saponifiedcellulose ester" is used to denote products of this type. Such productscan be coloured by means of dyestuifs having direct aflinity forcellulose, e. g. direct cotton colours. However, the production in thisway of dark shades which are of satisfactory fastness, particularly torubbing, is attended ,with some dificulty owing to the fact that onlyapart of the material is avail.-

able to carry the large proportion of dyestufi which is necessary toproduce the desired shade.

According to the invention, valuable. dark shades of very good fastnessproperties are obtained on surface-saponifled cellulose ester textilematerials by applying to or forming on the materials, together orseparately, a dyestufi (which term is used as including a mixture of'dyestufis) for the cellulose ester core and a dyestufi for thecellulose sheath, the latter dyestufl' being of such nature and presentin such proportion as to impart a grey or other neutral shade to tilematerials in the absence of the former dyes uff.

Most conveniently the ready formed dyestuifs dyestufis, should haveamnity for the cellulose core and the other for the sheath. Preferablythe colour-yielding substance which has aflinity for the core has nosubstantial afllnity for the v sheath, and vice versa. Instead of eitherof the colour-yielding substances, there can be used such a mixture ofcolour-yielding substances as will produce the desired shade. v

The'invention includes the products obtainable I by the above definedprocess, i. e. surface-saponi- 'fied cellulose ester materials having adark colour due to the presence in the core and sheath respectively ofdyestuffs having 'direct aflinity for the cellulose ester and forcellulose respectively, or which-have been formed on the materials fromother colour-yielding substances having such aflinity,'the dyestufi inthe sheath being of such nature and present in such proportion as toimpart a grey or other neutral shade to the materials in the absence ofthe dyestuii for the core.

The dark shades contemplated in accordance with the invention aretertiary shades such as browns, navy blue, bottle green, khakis, drabsand the like; Such shades resemble the neutral shades in that theyabsorb a proportion of light of each wave-length, but difi'er. in thatthey show a marked preferential reflection in some regions of thevisible spectrum. Where the colour-yielding substance is a dbazotisableamine it can be converted to the requisite dyestuii on the materials bydiazoti'sation and coupling withan appropriate coupling component.Similarly a coupling component on the materials can be converted bytreatment with a suitable diazotised aromatic amine. Again, in the caseof a leuco yat dyestuff or a reduced sulphur dyestufl conversion iseffected by oxidation. The dlazotisable amines which can be used ascolour-yielding substances in accordance with the invention canthemselves be dyestufis. An example of such an amine having amnity forthe sheath is a diazotlsable directcotto n colour.

The preferred dyestuif forthe sheath is a direct cotton colour. Thisdirect cotton colour can,

as mentioned above, be one which requires diazotisation and delevopment,e. g. with p-naphthol, to produce the desired grey or other neutralshade.

For the core, there can be used any dyestuii having afiinity forcellulose estermaterlals, or which has been formed on the materials froma colour-yielding substance having such afliinity. Advantageously, thedyestuii for the core is one which, in the absence of the dyestufl forthe sheath, would give a. primary or secondary shade, e. g. yellow,orange, red, blue or green. 7

Whenusing dischargeable direct cotton colours and dischargeablecellulose acetate dyestuffs it is possible toobtain dischargeable darkshades,

v 1% Chlorazol 1.25% Demo a result which is often rather difficult toobtain on cellulose acetate materials, since the dyestuffs available fordyeing in dark shades are not as a rule readily dischargeable.

As mentioned above the two dyestuffs may be I the colouration ofproducts obtained by surface saponiflcation of textiles of commercialacetonesoluble cellulose acetate. Such an acetone-soluble celluloseacetate contains about 52-55% of acetyl calculated as acetic acid, whilethe product derived from it by surface saponiflcation and Example 2' v Acloth similar to that treated in Example 1 is simultaneously dyed from asoap bath with /2% amino-azo-benzene for the core and 2% Diazo FastGreen GFLfor the surface layer.

After rinsing it is diazotised and washed, and

is then developed in with fl-naphthol. The resultant shade is a fullmaroon, being the composite eflect of a grey colouration in the sheathface-saponifled cellulose triacetate or other surwhich can be colouredaccording to the invention may contain, for example, -50% of acetyl.

The saponification may be carried out by any desired method provided theconditions are controlled so that only surface saponification occursleaving the core substantially unaltered. Examples of suitableconditions for efiecting this surface saponiflcation are to be found inU. S. Patent No. 1,897,691 and British Specification No.

The invention is illustrated by the following examples:

Example 1 A plain woven fabric composed of yarns of a surfaoe-saponifledcellulose acetate of acetyl value about is dyed from a soap or fattyalcohol sulphate bath containing a direct cotton colour capable ofyielding a grey or blackish shade on the cellulose sheath and acellulose acetate dispersion dyestufl capable of yielding a pale tomedium depth of a primary or secondary shade in the acetate core.

Suitable combinations of dyestuffs and the shades obtained are givenbelow. The percentages ofdyestuifs are based on the weight of thefabric.

Direct cotton colour Cellulose acetate dyestufl v Shade 1% ChlorazolFast 5% 4:4-diamino-3:3'- di- Sage green.

Black BKS. nitro-diphenyl me:

theme (10% aqueous paste).

3% 4-nitro-2'-5'-dimethyl-'4-aminoazobenzone (10% aqueous paste).

5% l-methylsmino-4- hydroxyethyi-aminoanthraquinone (10% aqueous paste).

4% 4:4-diamino-3:3- dinitro-diphenyl-methane (10% aqueous paste) plus 2%l-methyl-amino-i-hydroxyethylamino-anthraquinone (10% aqueous paste).

Fast Chocolate brown.

Black arts.

37 Chlorazol Fast Nav blue.

black BKS. y

1% Chlorazol Bottle green.

Black BKS.

Fast

3% +11 itro-2:5'-dime thyl-4-aminoazo benzene (10% aqueous paste).

3% 4-nitro-2:5-dimethyl-4-aminoazo benzene (10% aqueous paste).

0,75% Benzo m Tan brown. Grey BM Similar results are obtained byapplying the dyestuffs separately in either order, the acetate dyestuiffrom a soap bath and the direct cotton colour from a salt bath.

stufl being of such nature and present in such proportion as to impart aneutral shade to the materials in the absence of the former dyestuff.

' 2. Process for the coloration of surface-saponifled cellulose estertextile materials in dischargeable dark shades, which comprises applyingthereto a dischargeable dyestufl having direct affinity for thecellulose ester core and a dischargeable dyestufl, having directafllnity for the cellulose sheath, the latter dyestuff being of suchnature and present in such proportion as to impart a neutral shade tothe materials in the absence of the former dyestuff.

3. Process for the coloration in dischargeable dark shades of materialsobtained by surfacesaponiflcation of textile materials of commercialacetone-soluble cellulose acetate, which comprises applying thereto adischargeable dyestufl having direct afllnity for the cellulose estercore and a dischargeable dyestufl having afllnity 'for the cellulosesheath, the latter dyestuf! being of such nature and present in suchproportion as to impart a neutral shade to the materials in the absenceof the former dyestufl.

4. Process for the .coloration in dischargeable dark shades of materialsobtained by surface-' saponiflcation of textile materials of commercialacetone-soluble cellulose acetate, which comprises applying thereto adischargeable dyestufl having direct aillnlty for the cellulose estercore and a direct cotton color, the latter dyestuif being of such natureand present in such proportion as to impart a neutral shade to thematerials in the absence of the former dyestuff.

5. Surface-saponifled cellulose ester textile materials having adischargeable dark color due to the presence in the cellulose ester coreand the cellulose sheath respectively, of dischargeable dyestuffs forthe cellulose ester and for cellulose respectively, the dyestuff in thesheath being of such nature and present in such proportion as to imparta neutral shade to the materials in the absence of the dyestuif in thecore.

6. Surface-saponifled cellulose acetate textile materials having adischargeable dark color due to the presence in the celluloseacetatecore and the cellulose sheath respectively, of dischargeable 'dyestufisfor the celluloseacetate and for cellulose respectively, the dyestufl inthe sheath being and in the cellulose sheath of a direct cotton color,the direct cotton color being ot'such nature and present in suchproportion as to impart a neutral shade to the materials in the ab- 1sence of the dyestufl in the core.

8. Surface-saponifleu, cellulose ester-textile materials having a darkcolour due to the presence in the cellulose ester core and cellulosesheath respectively of dyestuffs for the cellulose ester and forcellulose respectively; thedyestufl in the sheath being of such natureand present in such proportion as to impart a neutral shade to' thematerials in the absenceof the dyestuil in GEORGE HOLLAND ALEXANDER Jamswnssou.

the core.

